Invariably, with few exceptions, when I query offerings described as "Qing," or "1910s" or "1940s" or "Deco," what I get is a variation of "Oh, it just looks like that style to me."

Second-hand provenance from heirs selling off old pieces from estates is equally deceptive - they tend to make up stories to fit their remembrances, not what actually occurred. For example, describing a necklace that is clearly 1970s-80s beads as 1940s because Dad was in the navy then near China and can only have bought it for Mom when he was there. You will recollect my recent post about a carnelian and cloisonne necklace thought to be purchased in the 1930s. German advisors were indeed employed in China in the 1930s - but did Dad buy this necklace for Mom then, or in later years? The people who actually know what happened are dead.